This invention relates in general to systems for monitoring pneumatic tires on moving vehicles and in particular to systems which utilize magnetic fields to detect changes in the temperature of a rotating pneumatic tire.
The increasing costs associated with the purchase and maintenance of motor vehicles makes it important that these vehicles be maintained as well as possible. Further, the safety considerations necessary with the high speed of operation typically associated with highway travel dictate that the operator be aware at all times of situations which can suddenly and drastically affect the operation of his vehicle.
One subsystem within a modern automobile which must be constantly maintained at peak condition in order to maximize the efficiency and safety of a motor vehicle is the pneumatic tires which support the vehicle. Excessive heating and improper inflation of pneumatic tires has long been recognized as a possible serious safety problem due to the possibility of sudden tire or tread failure, giving rise to possible hazardous conditions. While the measurement of tire pressure and the observance of tire temperature is a simple matter while a vehicle is stationary, it is a matter which is most difficult to observe during vehicle movment. Further, a tire problem often occurs only after a vehicle has been in motion for some time. Accordingly, it is desirable to have a method and apparatus which permits a pneumatic tire to be monitored while the vehicle which is supported by the tire is moving.
Several tire pressure and temperature monitoring systems are known in the prior art. Typically the systems utilize a complex wiring technique or utilize specialized transmitter and receivers which require power sources and antennae. Certain simpler monitoring apparatus are known and utilize self-contained pressure monitors which actuate a visible signal on the tire valve stem when the tire pressure is low. However, tire temperature is, more often than not, a more valid indication of imminent tire failure and all of these prior art systems fail to disclose a simple, reliable temperature sensor system which can be utilized with a rotating tire. Such a system could easily detect the increased tire temperature associated with imminent tire failure, or with tread separation in the case of a new or retreaded tire such as those typically utilized by truckers or drivers of other transport vehicles.